大庆长垣辫状河砂体物理模拟实验研究与认识

以大庆油田葡I23单元辫状河砂体沉积背景为基础设计沉积物理模拟实验，通过6个轮次实验，识别并分析了辫状河道、心滩、废弃河道、堤岸沉积、越岸沉积5种主要微相类型及其分布特征。其中河道及心滩坝沉积广泛发育，占到辫状河沉积的90%左右, 心滩坝多发育在河道中下游,心滩坝与心滩坝之间连通程度较高，连通部分约占心滩厚度的60%～80％，且心滩下部连通性好，上部较差。建立了沉积微相砂体构型参数相关关系及物性参数模型，初步认为河道砂体的宽厚比为70～120，长宽比为3～5；心滩坝砂体宽厚比为80～100，长宽比为1～3。河道面孔率分布区间为10%~11%，向上有逐渐变小的趋势；心滩坝面孔率分布区间为9%~10%，剖面上变化趋势不明显,心滩坝的中心部位夹层几乎是近似水平的，绝大多数情况下倾角小于3°,在长轴方向上迎水面夹层稍陡（＜5°）而背水面较平缓，短轴方向夹层在心滩两翼略有倾斜（＜8°）。研究对大庆油田辫状河储层沉积微相内部构型参数预测具有重要意义。

A study of braided river sand deposit in Changyuan,Daqing through physical simulation experiments

Physical simulation experiments were conducted based on the braided river sand deposit of the Daqing Oilfield unit PI23 as the background.Through six rounds of experiments,the five main microfacies types,i.e.the braided channel,the heart beach,the abandoned channel,the embankment deposit and the overbank deposit,and their distribution patterns were identified and analyzed.Among them,the braid channel and the heart beach deposits are widely developed,accounting for about 90% of the braided river deposits.Heart beach bar more developed in the middle and lower reaches of the river;the connectivity between the heart beach bars is of a higher degree and the mutually connected heart beach bars may account for 60 to 80 percent of the beach thickness.The connectivity in the lower part of the heart beach is good and in the upper part is poorer.At the same time,the correlation between the configuration parameters of sedimentary microfacies sand body and the model of physical parameters were established.The preliminary view is that the width to thickness ratio of the channel sand body is between 70 and 120,and the aspect ratio is between 3 and 5.The width to thickness ratio of heart beach bar sand body is between 80 and 100,and the aspect ratio is between 1 and 3.The distribution range of river face rate is 10%-11% with the trend of being gradually smaller upward.The distribution range of heart beach bar face rate is 9%-10% without obvious variation in the profile.The sandwich of the heart beach bar in the center part is approximately horizontal and in most cases the inclined angle is less than 3°.In the long axis direction,the sandwich on the meeting water side is little steep(<5°) while on the back water side is relatively flat.In the short axis direction,the sandwich is slightly inclined in two wings of the heart beach(<8°).The study is of great significance for forecasting the internal configuration parameters of the main sedimentary microfacies of braided river deposit in Daqing Oilfield.